Physics - Light (Reflection, Spherical Mirrors)

Reflection of Light: The phenomenon of bouncing back of light into the same medium when it strikes a polished surface. The Laws of Reflection state that $\angle i = \angle r$ and the incident ray, reflected ray, and the normal at the point of incidence all lie in the same plane.

Spherical Mirrors: These are mirrors whose reflecting surfaces are parts of a hollow sphere. A Concave mirror is silvered on the outer surface (converging), while a Convex mirror is silvered on the inner surface (diverging).

Principal Terms: The geometric center of the mirror is the Pole ($P$). The center of the hollow sphere is the Center of Curvature ($C$). The distance $PC$ is the Radius of Curvature ($R$).

Principal Focus ($F$): For a concave mirror, it is a point on the principal axis where rays parallel to the axis actually meet after reflection. For a convex mirror, rays appear to diverge from this point.

Focal Length ($f$): The distance between the pole $P$ and the principal focus $F$. For spherical mirrors of small aperture, the focal length is half the radius of curvature: $f = \frac{R}{2}$.

New Cartesian Sign Convention: All distances are measured from the Pole ($P$). Distances in the direction of incident light are positive; opposite to incident light are negative. Heights above the principal axis are positive ($+h$), and below are negative ($-h$).

Magnification ($m$): The ratio of the height of the image ($h_i$) to the height of the object ($h_o$). If $|m| > 1$, the image is magnified; if $|m| < 1$, it is diminished. A negative $m$ indicates a real and inverted image, while a positive $m$ indicates a virtual and erect image.